A brief description of the Horvitz (1954) technique follows: Samples 

 are collected by means of a hand auger or a mechanical drill from a 

 depth of 8 to 12 feet, placed in a pint jar, sealed, and shipped to the laboratory. 

 Broad reconnaissance surveys are carried out by taking samples at 1/4 to 1/2 

 mile intervals. Samples found to be of interest indicate areas which then are 

 sampled in a denser pattern. 



A sample of about 100 grams is treated first in a partial vacuum with an 

 aqueous solution of copper sulphate, then by phosphoric acid. The copper 

 sulphate prevents the acid from reacting with the carbide chips from the auger, 



Figure 28-3. Soil analysis for ethane and propane. 

 Small symbols indicate wells drilled before and 

 large symbols wells completed after the soil 

 survey. Station interval is 500 feet. Production 

 is from Miranda sand at 1500 feet (Horvitzj. 



which could produce spurious methane. The acid decomposes any carbonates 

 present and facilitates the release of hydrocarbons. The carbon dioxide is 

 removed with potassium hydroxide and the flask containing the sample then is 

 heated for 30 minutes at 100C. This mild treatment does not decompose the 

 included organic matter. The sample, now free of carbon dioxide, is collected 

 in an evacuated tube and analyzed. After the gaseous extract is cleaned with 

 potassium hydroxide solution, concentrated sulphuric acid, ascarite and phos- 

 phoric anhydride, the gas is separated into fractions of (1) methane, and (2) 

 ethane and heavier hydrocarbons. Each fraction is analyzed separately. Liquid 

 nitrogen (-196C) affects the separation, as methane remains gaseous while the 

 ethane fraction condenses at this temperature. The amount of methane is de- 



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